The embodiments described herein relate generally to detector calibration, and, more particularly, to calibration, calibration verification, and sensitivity checks for a detector. More specifically, the methods and systems include calibrating a detector by releasing a calibrant from a calibrant chamber in flow communication with the detector. The systems and methods further include verifying the calibration by releasing a verification substance from a verification chamber in flow communication with the detector. The systems and methods further include checking a sensitivity of the detector by releasing a sensitivity substance from a sensitivity chamber in flow communication with the detector.
Mobility spectrometers measure the intensity of ions arriving at a detector as a function of their drift time in order to characterize a sample. Because this drift time is dependent on experimental conditions, such as temperature and pressure, a drift time axis of the detector needs to be calibrated prior to sample analysis. When a detector is calibrated, absolute drift times are converted into “calibrated units,” such that peak positions of detected ions are compared to a library entry. Verification of the calibration may be performed by introducing a sample including a known verification substance into the detector, and confirming that the calibrated units enable accurate characterization of the known verification substance. In addition, a sensitivity check to verify that the detector is configured to detect a minimum amount of a substance may be performed. The sensitivity check may be performed by introducing a sample including a known amount of a known sensitivity substance into the detector, and confirming that the detector detects the known sensitivity substance.
In at least some known systems, calibration of the detector is performed using external calibrant traps, wherein the calibrant is introduced into the detector through a desorber. These calibration traps, however, have limited lifetimes, can get contaminated, and can be costly to replace and/or refill. Moreover, these calibration processes with external traps are labor-intensive and are not easily automated. Likewise, verification of the calibration and the sensitivity checks may be performed using external traps containing the verification and sensitivity substances, respectively. These external traps face the same drawbacks described above.
Accordingly, having a system that solves and/or eliminates these issues would be desirable.